In what sense? Are you looking for a ground cover for paths between rows that chickens will eat? I mean, if they are dedicated chicken rows, you could just sow quick-growing forage crops mixed with a soil building plant guild, for which there will be a lot of overlap, and let them go at it.
I would section off any crops at chicken level that you don't want them to taste (read: rip to tiny pieces before they decide they want the bugs growing in the root zone), and depending on number of chooks and length of individual rows, I would probably let them at only one row at a time.
If you used something like cattle panels to keep the chooks out of the garden rows, you could supplement their feed in two ways: by growing either a chicken-friendly crop that you could share by planting it on the perimeter of the garden rows, such that a third of the grown plant would poke out of the cattle panel for chicken feed, but remain otherwise sheltered, for continuous growth and to provide two thirds of those plants for human consumption; the garden rows could also use a chicken-edible ground cover mix including clovers, but basically more soil-building plants suitable for ground cover that would overgrow the barrier and get eaten by the chickens, only to regrow until the chickens got to them again. Rinse and repeat.
I would probably dig micro-swales between garden rows and chicken rows, at least a foot deep and around one shovel width wide (though more narrow if necessary for narrower rows), and I would fill them with a mix of wood chips, coffee grounds, and finished compost. They would act as soil bioreactors, especially if the area is treated with a good aerated compost extract before planting, and the swales treated with a mushroom slurry, either culinary in nature, or sourced from undisturbed, healthy-looking ground near your garden or in your neighbourhood. Beneficial insects would outcompete the bad ones you want to kill, and chickens would eat the surplus.
The soil life systems fostered by the micro-swales would most easily break down the chicken droppings, and the fungal networks would move minerals and nutrients where they were needed.
What to plant specifically depends largely on where you are and what the climate is like. More information would allow for more precise and useful advice.
Good stuff. Let us know how it goes, and good luck.
A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.
-Robert A. Heinlein